[Nexus 7 (2013) Q&A] k23m:
Quick Links

if fastboot mode is not available, try Unbricking Guide

if fastboot mode is available, do RESTOCK

In this thread I would like to consolidate information about eMMC flash memory failures and remedies.

When flash memory fails it becomes inaccessible or unwriteable with errors like the following:

sending 'bootloader' <3911 KB>...
OKAY [ 0.202s ]
writing 'bootloader'...
FAILED <remote: flash write failure>
or
E:can't mount /cache/recovery/last_install
E:can't open /cache/recovery/last_install
E:failed closing /dev/block/platform/msm_sdcc. 1/by-name/misc (I/O error)
E:failed to mount /cache (Invalid argument)
or
E:Unable to find partition size for '/boot'
E:Unable to find partition size for '/recovery'
E:Unable to find partition size for '/misc'
E:Primary block device '/dev/block/platform/msm_sdcc.1/by-name/userdata' for mount point '/data' is not present!
E:Unable to mount '/data'
E:Unable to recreate /data/media folder.

dmesg...
mmc0: error -110 whilst initialising MMC card

We observe these hardware failure symptoms:

device is totally dead

dead but flashes a few times the white LED next to USB port

dead but with active USB on PC device list

works up to fastboot stage or Google logo

may slowly boot Android sometimes

intermittently Android does not boot or work at all

#1 - eMMC unrelated

#2 - battery fault is most likely

#3 - catastrophic eMMC failure or GPT/bootloader damage, PC registers a new USB\VID_05C6&PID_9008 device, refer to QPST diagnostics below

#4 - partial eMMC failure or OS error, refer to fastboot diagnostics below

#5 - probably eMMC failure, unlocking and TWRP tests are required - post your logs

#6 - unlikely eMMC fault

Fastboot Diagnostics​

If your bricked unit still works in fastboot mode then please do the following tests:

boot the Nexus in fastboot mode (when off press power+vol.dn)

connect it to your PC

on PC run:

fastboot oem gpt-info

fastboot format cache
​

You can run the fastboot app from Windows or Linux...

on Windows get RESTOCK and run it from the 'data' folder

or run it from live Linux

If you get "partition[30].size 27852783 KB" then your eMMC chip is from Kingston (very high failure rate).

If the format command freezes at any stage, then the eMMC chip is faulty and needs to be replaced.

The normal format output takes only 1 second and is:

Creating filesystem with parameters:
Size: 587202560
Block size: 4096
Blocks per group: 32768
Inodes per group: 7168
Inode size: 256
Journal blocks: 2240
Label:
Blocks: 143360
Block groups: 5
Reserved block group size: 39
Created filesystem with 11/35840 inodes and 4616/143360 blocks
erasing 'cache'...
OKAY [ 0.359s]
sending 'cache' (10984 KB)...
OKAY [ 0.359s]
writing 'cache'...
OKAY [ 0.484s]
finished. total time: 1.203s

QPST Diagnostics​

Please upload your bricked device's memory dump for investigation. Just try the unbricking guide.

download "New Qualcomm 2012.rar"

extract the "fre" folder

connect your N7 to PC and when asked for a driver point it to the above folder

download "New_Qualcomm_QPST-2.7.422.zip"

extract it and run "setup.exe"

run Start/QPST/MemoryDebugApp.exe

in Memory Debug keep clicking "Browse" until you see a new COM port

in Memory Debug click "Get Regions"

in Memory Debug select and save "CODERAM.BIN"

upload "CODERAM.BIN" here

Repair Options​

ASUS service - apparently they can now do it for free with paid shipping!

motherboard replacement - for example this one "pulled from a working unit" for $25

RIFF JTAG Box - while the box is not cheap it can be used for other devices too (v1 was $109). Optional tool.

off-circuit eMMC programming and chip replacement - it is difficult and expensive but feasible

in-circuit Service ROM flashing - after chip replacement or if eMMC is OK but with damaged partition table or bootloader

eMMC chip replacement​

do not replace it with another Kingston

search for eMMC in FBGA 153 or 169 package

you can upgrade it to a higher capacity memory

new high-performance eMMC v5.1 requires updated software, available here

Nexus 7 2013 uses 3 brands of eMMC chips: Kingston, Hynix and Toshiba.

Kingston was initially identified as

unreliable

in this post a few years ago:

The above file is for RIFF JTAG flasher.

My Nexus 7 JTAG collection:

Asus_Nexus_7.rar

Asus_Nexus_7.txt

nexus7 jtag.jpg

RIFF Box JTAG GettingStarted.pdf

RIFF Box JTAG Manager Setup v1.56.exe

Please post your Nexus 7 2013 eMMC maker in this thread.

So far I have collected the following reports:

BRICKED Kingston Hynix Toshiba
-------------------------------------------
graphdarnell 1
fuser-invent 1
aungmyoswe 1
marc1706 1
micl9 1
consumer61 1*
bl4cKz4cK 1
patmann03 1
CWempe 1
purian23 1
NX3 1
ali1234 1
lowridincrew 1
DaWeIII 1
HTC Tytn... 1
jaybea 1
vfrvulcan 1
TechnicsKuzya 2
barbuda 1
Snoob25 1
Dazmatic 1
459below 1
amix 1
hypochondrej 1

WORKING Kingston Hynix Toshiba
-------------------------------------------
fuser-invent 1
k23m 2
yosmokinman 2
Tmzdroid 1
graphdarnell 1 2
OrBy 1
mydian 1
quickdraw86 1
micl9 1
tegodwin 1*
noahvt 1
Carrick Glen 1*
Axel85 1
NTRNSTR 1

*2015 production

To check the chip in working units use this app or dmesg:

Kingston (MMC32G)
-----------------
mmc0: new HS200 MMC card at address 0001
mmcblk0: mmc0:0001 MMC32G 28.8 GiB

Hynix (HBG4e)
-------------
mmc0: new HS200 MMC card at address 0001
mmcblk0: mmc0:0001 HBG4e 29.1 GiB

Toshiba (016G92)
----------------
mmcblk0: mmc0:0001 016G92 14.6 GiB

It is not so simple with bricked units but this device is exceptionally easy to disassemble. The chip is on the bottom of the motherboard but unlike the top, it is not covered with any shield (the purple chip).

:good: